is a municipality
located in the Belgian
province of Flemish Brabant
. The municipality comprises the towns of Mazenzele and Opwijk proper. On January 1st, 2000 Opwijk had a total population of 11,718 (5,745 males and 5,973 females). The total area is 19.89 km²
which gives a population density
of 589.14 inhabitants per km².